Pacemaker management for acute onset of heart block in childhood

Pediatric Post–Cardiac Arrest Care: A Scientific Statement From the American Heart Association

Successful resuscitation from cardiac arrest results in a post–cardiac arrest syndrome, which can evolve in the days to weeks after return of sustained circulation. The components of post–cardiac arrest syndrome are brain injury, myocardial dysfunction, systemic ischemia/reperfusion response, and persistent precipitating pathophysiology. Pediatric post–cardiac arrest care focuses on anticipating, identifying, and treating this complex physiology to improve survival and neurological outcomes. This scientific statement on post–cardiac arrest care is the result of a consensus process that included pediatric and adult emergency medicine, critical care, cardiac critical care, cardiology, neurology, and nursing specialists who analyzed the past 20 years of pediatric cardiac arrest, adult cardiac arrest, and pediatric critical illness peer-reviewed published literature. The statement summarizes the epidemiology, pathophysiology, management, and prognostication after return of sustained circulation after cardiac arrest, and it provides consensus on the current evidence supporting elements of pediatric post–cardiac arrest care.

Indications for permanent pacing in dogs and cats

Pacemaker implantation is considered as a standard procedure for treatment of symptomatic bradycardia in both dogs and cats. Advanced second-degree and third-degree atrioventricular blocks, sick sinus syndrome, persistent atrial standstill, and vasovagal syncope are the most common rhythm disturbances that require pacing to either alleviate clinical signs or prolong survival. Most pacemakers are implanted transvenously, using endocardial leads, but rarely epicardial leads may be necessary. To decide whether a patient is a candidate for pacing, as well as which pacing modality should be used, the clinician must have a clear understanding of the etiology, the pathophysiology, and the natural history of the most common bradyarrhythmias, as well as what result can be achieved by pacing patients with different rhythm disturbances. The goal of this review was, therefore, to describe the indications for pacing by evaluating the available evidence in both human and veterinary medicine. We described the etiology of bradyarrhythmias, clinical signs and electrocardiographic abnormalities, and the choice of pacing modality, taking into account how different choices may have different physiological consequences to selected patients. It is expected that this review will assist veterinarians in recognizing arrhythmias that may require permanent pacing and the risk-benefit of each pacing modality and its impact on outcome.

Long-term Intrinsic Rhythm Evaluation in Dogs with Atrioventricular Block

Background

Atrioventricular block (AVB) is a conduction abnormality along the atrioventricular node that, depending on etiology, may lead to different outcomes.

Objectives

To evaluate variations of intrinsic rhythm (IR) in dogs that underwent pacemaker implantation (PMI).

Animals

Medical records of 92 dogs affected by 3rd degree atrioventricular block (3AVB), advanced 2nd degree AVB (2AVB), paroxysmal 3AVB, 2:1 2AVB, or 3AVB with atrial fibrillation (AF) were retrospectively reviewed.

Method

The patient IR was documented with telemetry on the day of 1 – (95% CI, 1–2), 33 – (95% CI, 28–35), 105 – (95%CI, 98–156), and 275 days (95%CI, 221–380) after PMI. According to AVB grade at different examinations, AVB was defined as progressed, regressed, or unchanged.

Results

In 48 dogs, 3AVB remained unchanged, whereas in 7 it regressed. Eight cases of 2AVB progressed, 3 regressed and 2 remained unchanged. Eight cases of paroxysmal 3AVB progressed and 3 remained unchanged. Four dogs affected by 2:1 2AVB progressed, 2 regressed, and 1 remained unchanged. All cases with 3AVB with AF remained unchanged. Regression occurred within 30 days after PMI, whereas progression was documented at any time. Variations in IR were associated with type of AVB (P < .03) and time of follow‐up (P < .0001).

Conclusions and clinical importance

The degree of AVB assessed at the time of PMI should not be considered definitive because more than one‐third of the cases in this study either progressed or regressed. Additional studies would be necessary to elucidate possible causes for transient AVB in dogs.

Seizures and syncope due to complete atrioventricular block in a patient with acute myocarditis with a normal left ventricular systolic function

A 43-year-old man was admitted to our hospital presenting with seizures and syncope. He had a history of a cold with a fever of 39°C occurring three days earlier. Electrocardiography (ECG) showed complete atrioventricular block (AV block) with a maximum pause of 32 seconds, for which temporary pacing was performed. Echocardiography showed mild hypertrophy of the left ventricle (LV) with a normal ejection fraction of 61%. Coronary angiography showed normal coronary arteries. Then, an endomyocardial biopsy was performed, the results of which indicated a diagnosis of acute myocarditis. After admission, the complete atrioventricular block disappeared together with normalization of the LV wall thickness.

Myocarditis complicated by complete atrioventricular block: nine years' experience in a medical center

BACKGROUND

Myocarditis complicated with complete atrioventricular block (CAVB) is rare in children. The purpose of this study was to report the outcome of myocarditis with CAVB in our institution.

METHODS

Between June 1998 and June 2007, nine pediatric patients (aged from 1.5 to 16 years) were admitted, presenting with acute myocarditis with CAVB. We analyzed their clinical presentations, biochemistry and serology studies, chest X-rays, electrocardiograms, echocardiography, complications and outcomes.

RESULTS

Hypotension and Stokes-Adams seizures occurred in five and four of our patients, respectively. Cardiomegaly of chest X-ray was common in eight (89%) of our patients. Echocardiography revealed impaired left ventricular performance in three patients. Six patients suffered ventricular tachycardia (VT). Three cases of VT occurred before pacemaker implantation and the others occurred afterwards. Eight patients survived. Six of them regained sinus rhythm within 12 days (range 1-12 days), and two had a right bundle branch block at follow-up. Two patients had persistent CAVB, and one received permanent pacemaker implantation; the other received supportive care. One patient died due to persistent low cardiac output and a new onset of VT on the 4th admission day. During a follow-up period of 56+/-27 months, all eight surviving patients remained asymptomatic.

CONCLUSIONS

The outcome of CAVB complicated with myocarditis is variable. Most of our patients resumed normal heart function. The incidence of persistent CAVB was 22%. VT is a common and serious complication, but it can be effectively treated medically. Persistent low cardiac output after pacemaker implantation and late onset VT should be considered as risk factors of mortality.

Complete atrioventricular block persisting after regression of infectious myocarditis

Atrioventricular block is usually transient during the course of infectious myocarditis. We report the case of a patient presenting with complete infra-hisian atrioventricular block occurring in the setting of infectious myocarditis and in whom a pacemaker should be finally implanted. Borderline serologies for picornavirus were present 6 weeks later. Complete atrioventricular block persisted during the two years of follow-up despite otherwise complete regression of the myocarditis. We then discuss the main features of conduction disturbances complicating infectious myocarditis, including a list as complete as possible of all the causal agents possibly involved.

Junctional ectopic tachycardia following complete heart block associated with viral myocarditis

We describe the case of an infant progressing from sinus rhythm to complete heart block, junctional ectopic tachycardia, and back to sinus rhythm as the only manifestation of viral myocarditis.

The clinical course of acquired complete heart block in children with acute myocarditis

A case of biopsy-proven myocarditis in a 7-year-old complicated by advanced atrioventricular (AV) block prompted a review of the medical literature to determine the prognosis for recovery of AV conduction or need for pacemaker implantation. A total of 40 patients younger than 20 years of age were identified, with return of AV conduction within 7 days in 27 patients (67%), permanent pacing in 11 patients (28%) with persistent AV block, and death in 2 patients (5%).

Complete AV-block in two children with immunohistochemical proven myocarditis

We report two children with acquired third degree AV-block caused by acute myocarditis. The diagnosis was proven by endomyocardial biopsy. Severe lymphocytic myocardial infiltration was shown using immunohistological methods. One of the children was treated with prednisone During therapy conduction disturbance nearly disappeared and infiltration was markedly reduced in a subsequent biopsy. In the other patient the parents refused immunosuppressive treatment and a permanent pacemaker was necessary for persistent bradycardia.

CONCLUSION

Immunohistological staining of an endomyocardial biopsy can be used to establish the diagnosis of myocarditis in patients with atypical clinical manifestation, such as complete AV-block, and can support the decision for therapy. In one patient improvement was documented by the disappearance of inflammatory activity in a repeated biopsy.

Mastering pediatric cardiopulmonary resuscitation

Premature and unexpected death, especially in children, is tragic and very unacceptable. Effective treatments for sudden death of pediatric patients continue to emerge. Modern cardiopulmonary resuscitation function began with the widespread introduction of closed-chest cardiac massage in 1960; however, despite 35 years of research and refinement, more than 90% of children who receive cardiopulmonary resuscitation do not survive. This article summarizes and expands on current treatment concepts for pediatric sudden death. Emphasis is placed on procedures and techniques that likely are accessible in most medical centers caring for critically ill and injured children.

Complete heart block in a child with varicella

A case of varicella myocarditis in a previously healthy 6-year-old child was reviewed. The patient presented with third-degree heart block and shock as the sole manifestation of her cardiac involvement. Bradyarrhythmias required temporary transvenous pacing. Intravenous acyclovir was used. The patient recovered without permanent sequelae. The natural history, clinical presentation, and treatment of varicella myocarditis are reviewed.

Life-threatening dysrhythmias in varicella myocarditis

Varicella myocarditis is an unusual complication of a common childhood disease. Two patients with life-threatening dysrhythmias and circulatory failure are reported. One patient required permanent pacemaker implantation for acquired complete heart block, not previously described with varicella infection. Previously reported cases of varicella myocarditis are reviewed.